Mercury vapor lamp



Nov. 8,1932. M. HULETT 1. 9

' MERCURY VAPOR LAMP Filed Feb. 20,-1923 I N VEN TOR.

VOLTAGE RMPEMQI 5455753w HlZ TIME IN Mmu'ras ATTORNEYS? Patented Nov. 8, 1932. v i I 1 3 400 UNITED sTAras PATENT OFFICE.

MASON nULE'rr, on NEW YORK, N. Y; ASSIGNOB B2 .MESNE Assrofimmrs, 'ro THE runnrcx coaromrron, or MILTON, W sconsin, 4 conrolmrron or DELAWARE MERCURY VAPOR LAMP Application filed February 20, 1923. Serial No. 620,190.- v

In operating high pressure mercury vapor accomplishing. this result comprises a circuit lamps, it is desirable to start the are at as in shunt to the lamp containing the heating low as amperage as possible. For the type means, which circuit is opened and closed by of lamp taking normally 3.5 to 4.0 amperes means of an automatic switch actuated by '5 the lowest practicable starting amperage has current flowing in the lamp circuit. been 8.0 to 10. This is due to the fact that The foregoing objects are attained by the p when a lower starting amperage than what arrangements illustrated in the accompanymay be called the critical starting value ining drawing in which herent to this type of lamp is used the are Fig. 1 shows a vapor electric lampprovided 10 is established with difiiculty and the build with a mercury cathodev and a hot anode;

up period is materially lengthened. It may Fig. 2 illustrates a slightly modified form be said that a criterion for the critical startof apparatus for automatically cutting out ing value, is that current at which, when the resistance; and lamp is started, the arc will be established Fig. 3 is a set of curves illustratlng certain promptly and will build up rapidly. The comparative results obtained by my invencritical starting value has been universally tion. accepted in practice to be from ap-proximate- Referring to the drawing in detail the refly 100% to as much as 200% in excess of the erence numeral 10 designates a high pressure normal operating or stable current value. mercury vapor lamp of the hot anode ty e My invention relates to an apparatus and supported in an adjustable holder 11 so that a method whereby this type oflamp can be the tube of the lamp may be located at a de-' started at a relatively low amperage, and at sired angle. 12 is a suitable heating coil of the same time retain and even improve the high resistance wire, 13 an automatic solebuild up characeristics as compared with the noid switch, and 14 the ballast resistance ordistarting of the lamp under the high critical nary to this type of lamp. The operation is starting current method heretofore employed. as follows: When the main switch 15 is closed In fact, my method enables me not only to the heating circuit becomes energized. Vastart the lamp materially below the critical por soon forms in the bulb 16 of the lamp as starting value but to obtain the normal op- Well as in the tube. After a few seconds so crating values immediately following the the mercury starts to boil with aresult that formation of the arc. This I accomplish, in the mercury level in the bulb falls with the particular apparatus shown, by heating a consequent extending of the mercury the mercury electrode. The heating of the body in the tube. As the heating conmercury causes vapor to form and build up tinues the mercury body in the tube appressure in the bulb of the tube which reproaches the anode 17 until contact is made. 35 sults in the lowering of the mercury level in The slight oscillation of the mercury column the bulb and the raising of the level in the in the elongated body of tube 10, which I have body of the tube until the mercury contacts heretofore mentioned, causes this contact to with the anode. I have observed that. there be broken immediately and this separation is a slight oscillation ofthe mercury in the of the mercury from the anode draws and 90 body of the tube and that, immediately after starts the arc. this contact, the mercury recedes and breaks As soon as the arc starts the switch 13 contact with the anode, thus striking an arc opens, breaking the contact 18 whereby the therebetween. Consequently with my method heating circuit is deenergized. Should the 46 it is not necessary to tilt the tube to strike arc fail for any reason the switch 13 closes 95 the arc, as is now the common practice. the contact 18 and the whole starting opera Another feature of my improved method tion is immediately repeate and apparatus consists in automatically start- It will be understood that when the starting the lamp again when the main operating ing amperage is limited by the amount of current fails to flow therein. The means for resistance in series with the lamp, the run- 100 lamp, I short-circuit a portion of the resist-- coils,

starting current limited to 4.5 amperes.

ning or normal operating voltage of the lamp will be limited to a certain value. en it is desired to increase the voltage across the an'ce at a predetermined point in the buildup of the lamp. For automatically cutting out of resistance, I prefer to use a device as shown in Fig. 2. 4 This device consists of two opposing coils 19 and 20 with cores of magnetic material. adapted to attract the lever 21, which is also of magnetic material. Upon the comparatively high starting current, the'pull of coil 20 is preponderant and the lever 21 is kept from closing upon contact 22. When the current falls to a predetermined value the pull of the coil 19 becomes preponderant, due to the diflerence in the reluctance of the magnetic circuits of these and the lever 21 closes upon contact 22, shunting coil 20 and a portion of the resistance 14. Electromagnetic switches having the operating characteristics above described are well known 1n the art. United States Patent No. 1,325,049 granted December 16,

1919, illustrates one form of such a switch.

It is readily appreciated that by the use of the mechanism just described, I am able to start the lamp at a desired low amperage and subsequently, if desired, increase the voltage to a higher value than that fixed by a current limiting resistance.

In the drawing I have illustrated the lamp. as having been so adjusted that when the proper temperature of the mercury electrode has been reached the same will contact with and then separate from the other electrode and thereby form the are. It will be readily understood, however, that my invention also contemplates the heating of the mercury electrode to the desired temperature and thereafter manually or automatically bringing the electrodes in contact.

I have found that the build-up characteristics of the lamp when started in the described manner can be varied by adjusting the position of the mercury in the lamp tube. This variation is shown in Fig. 3 where curves A show characteristic voltage and amperage curves when the lamp is started with the mercury body approximately one half inch from the anode 17. Curves B show the characteristic voltage and amperage curves when the lamp is started with the mercury body approximately two inches from the anode 17. v

The value and importance of this discovery is apparent by comparison of curves C and D in Fig. 3. Curves C show the characteristic build-up of a 110 volt lamp when operated in the ordinary manner with tlie t is readily appreciated why such a starting characteristic is impossible for a lamp in commercial use. The are is not established until eight minutes after being struck. Furplace between the mercury and of the are a violent play extending over a period of approximately two minutes takes the anode which is extremely objectionable. The operating characteristics of the lamp do not reach a stable condition until sixteen minutes after the start.

Curves D show the characteristic buildup under the same conditions prevailing from which curves C are taken when the means I have described are employed. It will be noted that the arc is established in less than one minute after being struck. The establishment of the arc is smooth with no fluctuations or objectionable features such as prevailed in the previous illustration. The operating characteristics are practically normal two minutes after starting, no change taking place in the voltage and a difference of but 0.2 amperes showing in the current curve.

I have illustrated and described herein the improved and preferred form of apparatus for carrying out themethod which I claim. It is to be expressly understood, however, that I do not limit myself thereto as changes ma be made in points of detail and other em odiments resorted to without deviating irom the true spirit and scope of my invenion.

What I claim is:

1. The combination with a vapor lamp having two electrodesone of which is mercury, of an electrically actuated heater for heating the mercury electrode and thereby causmg the same to approach the other electrode to establish contact therewith, a circuit for supplying current to the heater and the lamp electrodes, a relay for opening thecircuit to the heater when contact is established between the electrodes, a resistance in the circuit for controlling the voltage impressed between the electrodes, and a relay in the circuit acting automatically to increase the voltage impressed between the electrodes when the current flowing therebetween falls to a predetermined value.

2. The combination with a vapor lamp having two electrodes one of which is mercury, of an electrically actuated heater for heating the mercury electrode and thereby causing the same to approach the other electrode to establish contact therewith, a circuit for supplyin current to the heater and the lamp electro es, a relay for opening the circuit to the heater when contact is established between the electrodes, a resistance in said circuit for controlling the voltage impressed between the electrodes, and a relay operable when the current between the electrodes falls to a predetermined value to reduce said resistance and thereby increase the voltage impressed between the electrodes.

3. The method of starting a vapor arc electric lamp having a pair of main electrodes of which one is a vaporizable liquid, which consists in heating the liquid electrode below its surface to cause oscillations thereof toward and from the other electrode until the liquid momentarily contacts with the other electrode to start an arc therebetween, and automatically stopping the application of heat when the liquid contacts with the other electrode.

4. The method of starting a vapor are electric lamp having a main cathode of mercury and a rigid anode, which consists in applying heat to the cathode to create vapor pressure below its surface to produce oscillations thereof toward and from the anode until the mercury momentarily contacts with the anode to initiate the flow of current and the striking of an arc therebetween, and automatically interrupting the application of heat to the cathode when the cathode contacts with the anode.

5. The combination with a vapor arc lamp having an evacuated envelope in the form of an elongated tube with a mercury cathode adjacent one end and a rigid anode spaced from the cathode of an electric heater associated with the mercury to impart heat thereto beneath its surface to create pressure he hind the surface of the mercury to impel the same by a series of oscillations toward the anode, a circuit for supplying current to the heater, and means for interrupting the flow of current to the heater contacts with the anode.

In testimony whereof, I have hereunto set my hand this 17th day of February, 1923.

SON HULETT.

when the cathode 

